Abstract:
Die Erfindung betrifft eine Kathode mit einem mit einer Erdalkali-Verbindung imprägnierten Matrixkörper (1), auf desses Oberfläche eine Deckschicht (2,3,4) aufgebracht ist, welche hochschmelzendes Metall wie insbesondere Wolfram und Scandium enthält. Eine hohe Emission bei niedriger Betriebstemperatur und gleichzeitig eine schnelle Erholung nach Ionenbombardement sowie eine lange Lebensdauer werden dadurch erreicht, daß die Deckschicht wenigstens zwei Schichten unterschiedlicher Zusammensetzung enthält, wobei eine rein metallische Schicht (5,6,7) auf den imprägnierten Matrixkörper (1) aufgebracht ist, welche Scandium sowie ein hochschmelzendes Metall wie insbesondere Wolfram und/oder Rhenium enthält, und daß als abschließende Schicht eine metallische Schicht aus einem hochschmelzenden Metall wie insbesondere Wolfram aufgebracht ist.
Abstract:
An impregnated thermionic cathode comprises a porous matrix (12) of an alloy of a refractory metal together with a transition metal between 1 and 6%, with a meltable alkaline earth mixed oxide filling the pores of the matrix. The refractory metal may be of tungsten or molybdenum. The transition metal may be of iridium, osmium, rhenium or ruthenium. There may be an additional electron emissive layer (16) on the surface of the cathode which comprises over 25% of the transition metal.
Abstract:
A cathode body for an impregnated scandate cathode is obtained by compressing and sintering a mixture of tungsten powder with approximately 0.5% by weight of scandium, whereafter the body is impregnated.
Abstract:
According to the present invention, an impregnated cathode is provided wherein an alloy layer (19) of iridium and tungsten is formed on a surface of a porous pellet (11) impregnated with an oxide of an alkali earth metal, wherein a crystal structure of the alloy has an ell phase comprising an hcp structure whose lattice constants a and c satisfy 2.76 s a ≤ 2.78 and 4.44 ≤ c ≤ 4.46, respectively. The impregnated cathode of the present invention maintains stable electron emission characteristics from an early stage of operation.
Abstract translation:根据本发明,提供了一种浸渍阴极,其中在浸渍有碱土金属氧化物的多孔颗粒(11)的表面上形成铱和钨的合金层(19),其中晶体结构 合金具有包含hcp结构的εII相,其晶格常数a和c分别满足2.76和4.44 = c = 4.46。 本发明的浸渍阴极从早期的操作阶段保持稳定的电子发射特性。
Abstract:
Porous agglomerates (14) are made from pure tungsten by sintering fine particles together and mechnically breaking down the mass to form some agglomerates (14) considerably larger than the particles. These agglomerates (14) are mixed with fine iridium powder (18) and sintered to form a porous mass. The mass is machined to the cathode shapes (10') and impregnated with an alkaline earth aluminate (18). The large agglomerates (14) alloy with the iridium only on their outer surface. Their pure tungsten interior provides the surfaces to reduce the alkaline earth oxide to the metal which activates the cathode.
Abstract:
A dispenser cathode which comprises an emission surface (4), a reservoir for material releasing (2), when heated, work-function-lowering particles, and at least one passage (7) for allowing diffusion of work-function-lowering particles from said reservoir to said emission surface, said emission surface comprising at least one emission area (9) and at least one non-emission area (8) covered with emission-suppressing material and surrounding each emission area, said non-emission area comprising at least one passage connecting said reservoir with said non-emission area and debouching within a diffusion length distance from an emission area for allowing diffusion of work-function-lowering particles from said reservoir to said emission area.